On the utilization of modified red mud in dimethyl disulfide and methyl mercaptan emission abatement

In this paper, a novel application of industrial waste, namely red mud (RM), in the abatement of two malodorous and harmful sulfur compounds, dimethyl disulfide (DMDS) and methyl mercaptan (MM), is presented. The effects of calcination and activations with hydrochloric acid or a mixture of hydrochloric and orthophosphoric acid on the properties and performance of RM are compared using laboratory-scale experiments. The RM-based materials were characterized by XRF, XRD, FE-SEM, N2 -physisorption, TGA/DTA, and FTIR analyses. RM exhibits very promising catalytic properties in the abatement of both DMDS and MM. The hydrochloric acid-activated RM was the most active in both cases, which was explained by its rather high specific surface area (144 m2 g −1 ), higher contents of Fe2O3 and TiO2, as well as lower content of phosphorus. For both DMDS and MM, the main oxidation products were sulfur dioxide, carbon monoxide, and carbon dioxide. DMDS was observed as a reaction intermediate in MM oxidation. While the final conversions of DMDS and MM were high, the oxidation was not complete, indicated by the formation of carbon monoxide. Nevertheless, the modified RM appears as a very interesting alternative to the existing DMDS and MM abatement catalysts.Web of Science121art. no.

On the Utilization of Modified Red Mud in Dimethyl Disulfide and Methyl Mercaptan Emission Abatement

In this paper, a novel application of industrial waste, namely red mud (RM), in the abatement of two malodorous and harmful sulfur compounds, dimethyl disulfide (DMDS) and methyl mercaptan (MM), is presented. The effects of calcination and activations with hydrochloric acid or a mixture of hydrochloric and orthophosphoric acid on the properties and performance of RM are compared using laboratory-scale experiments. The RM-based materials were characterized by XRF, XRD, FE-SEM, N2-physisorption, TGA/DTA, and FTIR analyses. RM exhibits very promising catalytic properties in the abatement of both DMDS and MM. The hydrochloric acid-activated RM was the most active in both cases, which was explained by its rather high specific surface area (144 m2 g−1), higher contents of Fe2O3 and TiO2, as well as lower content of phosphorus. For both DMDS and MM, the main oxidation products were sulfur dioxide, carbon monoxide, and carbon dioxide. DMDS was observed as a reaction intermediate in MM oxidation. While the final conversions of DMDS and MM were high, the oxidation was not complete, indicated by the formation of carbon monoxide. Nevertheless, the modified RM appears as a very interesting alternative to the existing DMDS and MM abatement catalysts

Leaching of metals from red mud and toxicity in human cells in vitro

Toxicity of red mud, a waste from alumina production, was studied using human breast cancer MCF-7 cells. Culture medium was prepared by mixing water for 3 days with the red mud and removing solid particles afterwards (red mud water). Culture for 48 h of the cells in this medium in neutral pH decreased the cell viability, as analyzed by the MTT-test, and increased the formation of reactive oxygen species. Thus, neutralization does not eliminate the toxicity of red mud. In preliminary experiments, a combined effect of five metals (Cr, Li, V, Al, As) increased the formation of ROS (reactive oxygen species) statistically significantly. Each element separately did not have a similar effect. In environmental applications, red mud is likely to be used after activation. In this work, the red mud was activated using hydrochloric acid to study the physical and chemical properties before and after the treatment. Activation increased the specific surface area of red mud from 16 m2 g−1 to 148 m2 g−1, which is beneficial in many environmental applications such as in the adsorptive removal of pollutants. After activation, leaching of some elements from the red mud decreased (e.g. Al from 38.0 to 0.56 mg L−1, As from 21.0 to 2.1 μg L−1, V from 172.0 to 29.8 μg L−1) while some increased (e.g. Li from 0.04 to 2.81 mg L−1, Cr from 0.35 to 3.23 mg L−1).Web of Science332art. no. 13880

Leaching of metals from red mud and toxicity in human cells in vitro

Abstract Toxicity of red mud, a waste from alumina production, was studied using human breast cancer MCF-7 cells. Culture medium was prepared by mixing water for 3 days with the red mud and removing solid particles afterwards (red mud water). Culture for 48 h of the cells in this medium in neutral pH decreased the cell viability, as analyzed by the MTT-test, and increased the formation of reactive oxygen species. Thus, neutralization does not eliminate the toxicity of red mud. In preliminary experiments, a combined effect of five metals (Cr, Li, V, Al, As) increased the formation of ROS (reactive oxygen species) statistically significantly. Each element separately did not have a similar effect. In environmental applications, red mud is likely to be used after activation. In this work, the red mud was activated using hydrochloric acid to study the physical and chemical properties before and after the treatment. Activation increased the specific surface area of red mud from 16 m2 g−1 to 148 m2 g−1, which is beneficial in many environmental applications such as in the adsorptive removal of pollutants. After activation, leaching of some elements from the red mud decreased (e.g. Al from 38.0 to 0.56 mg L−1, As from 21.0 to 2.1 μg L−1, V from 172.0 to 29.8 μg L−1) while some increased (e.g. Li from 0.04 to 2.81 mg L−1, Cr from 0.35 to 3.23 mg L−1